[2] The first election to the council was held in 1964, initially operating as a shadow authority before the new system came into full effect in 1965.
The by-election was triggered by the death of Councillor Adrian Knowles of the Conservative Party.
The by-election was triggered by the resignation of Councillor Ben Johnson of the Labour Party, following his appointment as an adviser to the Mayor of London, Sadiq Khan.
[18] This by-election was triggered by the death of Councillor Sally-Ann Ephson of the Labour Party.
The by-election was triggered by the resignation of Councillor Kate Forbes of the Labour Party.